Thanks for your response. It's good to hear opinions from others on matters such as this. I would really like to have something like Tidal or JScape (
Managed File Transfer and Network Solutions) but it becomes quite difficult convincing the bosses to fork out and more so get the guys to move their systems over. We're fairly small scale in all this but have enough systems to be painful to migrate.
I think for now I'm going to go with polling "hot folders", move them onto DMZ host with some sort of ticket as part of our existing queuing systems and then let the DMZ host handle the transfer. If it fails transfer (from DMZ host to third party), it can create a queue file in a folder, which I can monitor out of Nagios to see if there are any pending transfers. At this point, the onus has moved off the internal processing systems, and if necessary certain departments can get spammed about "Failed to send to third party". If it fails copying from processing server to DMZ host then the files stay where they are anyway and I get spammed about "Failed to send to transfer system".
Hopefully this thread may help others who are facing similar situations in the area of manged transfer systems.